For conventional strain gauges, resistance wire strain gauges and semiconductor strain gauges are in widespread practice, and the gauge factor (the rate of change of an impedance per unit strain) is about 2 for resistance wire strain gauges, and about 150 for semiconductor gauges.
However, these gauge factor values are difficult to implement detection sensors for detecting minute strains and acceleration required for bioinstrumentation and high-accuracy industrial instrumentation. Strain gauges (stress sensors) having higher gauge factors must be developed.
With this being the situation, the present inventor previously invented a high-sensitivity strain gauge (stress impedance effect element) based on the stress impedance effect of a magnetostrictive amorphous wire (Japanese Unexamined Patent Application Publication No. 10-170355). This stress impedance effect element has achieved a gauge factor of 4000 using a CoSiB amorphous wire with a diameter of 20 μm, thereby allowing the detection of minute strain, stress, acceleration, and the like.